Want to know what is changing or what's new in the Active Directory space from Win2k8? Then follow this link.
I have to say that I am quite pleased with the Beta3 build that we are running in production (6001.16510). There have been no "show-stoppers" to date since we've started deploying which is a nice change to past operating systems we've rolled out during our dogfooding cycles. We've ran into some minor bugs that we've filed and fixed post-beta3 but all in all these machines are quite stable and running efficiently.
We have quite a few RODCs in production currently at Microsoft, some of those are running on server core others are on full server. We have a mix of x86 and x64 running in production also. AD as a service has been running without issue. Replication with 2k3 DCs, authentication, LDAP, etc have worked with little fanfare. Like I said we're running into some minor OS issues which were working on (that's why we do this), but I'm pretty impressed with the work that the product group has done on Win2k8.
Any horror stories out in the field with LH B3? Any bugs that are frustrating you with this build? Drop me an e-mail or post a comment and I'll check to see if we're handling your issue internally (as time permits).